networking/udhcp/files.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * files.c -- DHCP server file manipulation *
   4  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   5  */
   6
   7 #include <netinet/ether.h>
   8
   9 #include "common.h"
  10 #include "dhcpd.h"
  11 #include "options.h"
  12
  13
  14 /* on these functions, make sure your datatype matches */
  15 static int read_ip(const char *line, void *arg)
  16 {
  17         len_and_sockaddr *lsa;
  18
  19         lsa = host_and_af2sockaddr(line, 0, AF_INET);
  20         if (!lsa)
  21                 return 0;
  22         *(uint32_t*)arg = lsa->u.sin.sin_addr.s_addr;
  23         free(lsa);
  24         return 1;
  25 }
  26
  27 static int read_mac(const char *line, void *arg)
  28 {
  29         struct ether_addr *temp_ether_addr;
  30
  31         temp_ether_addr = ether_aton_r(line, (struct ether_addr *)arg);
  32         if (temp_ether_addr == NULL)
  33                 return 0;
  34         return 1;
  35 }
  36
  37
  38 static int read_str(const char *line, void *arg)
  39 {
  40         char **dest = arg;
  41
  42         free(*dest);
  43         *dest = xstrdup(line);
  44         return 1;
  45 }
  46
  47
  48 static int read_u32(const char *line, void *arg)
  49 {
  50         *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
  51         return errno == 0;
  52 }
  53
  54
  55 static int read_yn(const char *line, void *arg)
  56 {
  57         char *dest = arg;
  58
  59         if (!strcasecmp("yes", line)) {
  60                 *dest = 1;
  61                 return 1;
  62         }
  63         if (!strcasecmp("no", line)) {
  64                 *dest = 0;
  65                 return 1;
  66         }
  67         return 0;
  68 }
  69
  70
  71 /* find option 'code' in opt_list */
  72 struct option_set *find_option(struct option_set *opt_list, uint8_t code)
  73 {
  74         while (opt_list && opt_list->data[OPT_CODE] < code)
  75                 opt_list = opt_list->next;
  76
  77         if (opt_list && opt_list->data[OPT_CODE] == code)
  78                 return opt_list;
  79         return NULL;
  80 }
  81
  82
  83 /* add an option to the opt_list */
  84 static void attach_option(struct option_set **opt_list,
  85                 const struct dhcp_option *option, char *buffer, int length)
  86 {
  87         struct option_set *existing, *new, **curr;
  88
  89         existing = find_option(*opt_list, option->code);
  90         if (!existing) {
  91                 DEBUG("Attaching option %02x to list", option->code);
  92
  93 #if ENABLE_FEATURE_RFC3397
  94                 if ((option->flags & TYPE_MASK) == OPTION_STR1035)
  95                         /* reuse buffer and length for RFC1035-formatted string */
  96                         buffer = (char *)dname_enc(NULL, 0, buffer, &length);
  97 #endif
  98
  99                 /* make a new option */
 100                 new = xmalloc(sizeof(*new));
 101                 new->data = xmalloc(length + 2);
 102                 new->data[OPT_CODE] = option->code;
 103                 new->data[OPT_LEN] = length;
 104                 memcpy(new->data + 2, buffer, length);
 105
 106                 curr = opt_list;
 107                 while (*curr && (*curr)->data[OPT_CODE] < option->code)
 108                         curr = &(*curr)->next;
 109
 110                 new->next = *curr;
 111                 *curr = new;
 112 #if ENABLE_FEATURE_RFC3397
 113                 if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 114                         free(buffer);
 115 #endif
 116                 return;
 117         }
 118
 119         /* add it to an existing option */
 120         DEBUG("Attaching option %02x to existing member of list", option->code);
 121         if (option->flags & OPTION_LIST) {
 122 #if ENABLE_FEATURE_RFC3397
 123                 if ((option->flags & TYPE_MASK) == OPTION_STR1035)
 124                         /* reuse buffer and length for RFC1035-formatted string */
 125                         buffer = (char *)dname_enc(existing->data + 2,
 126                                         existing->data[OPT_LEN], buffer, &length);
 127 #endif
 128                 if (existing->data[OPT_LEN] + length <= 255) {
 129                         existing->data = xrealloc(existing->data,
 130                                         existing->data[OPT_LEN] + length + 3);
 131                         if ((option->flags & TYPE_MASK) == OPTION_STRING) {
 132                                 /* ' ' can bring us to 256 - bad */
 133                                 if (existing->data[OPT_LEN] + length >= 255)
 134                                         return;
 135                                 /* add space separator between STRING options in a list */
 136                                 existing->data[existing->data[OPT_LEN] + 2] = ' ';
 137                                 existing->data[OPT_LEN]++;
 138                         }
 139                         memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
 140                         existing->data[OPT_LEN] += length;
 141                 } /* else, ignore the data, we could put this in a second option in the future */
 142 #if ENABLE_FEATURE_RFC3397
 143                 if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 144                         free(buffer);
 145 #endif
 146         } /* else, ignore the new data */
 147 }
 148
 149
 150 /* read a dhcp option and add it to opt_list */
 151 static int read_opt(const char *const_line, void *arg)
 152 {
 153         struct option_set **opt_list = arg;
 154         char *opt, *val, *endptr;
 155         char *line;
 156         const struct dhcp_option *option;
 157         int retval, length, idx;
 158         char buffer[8] __attribute__((aligned(4)));
 159         uint16_t *result_u16 = (uint16_t *) buffer;
 160         uint32_t *result_u32 = (uint32_t *) buffer;
 161
 162         /* Cheat, the only const line we'll actually get is "" */
 163         line = (char *) const_line;
 164         opt = strtok(line, " \t=");
 165         if (!opt)
 166                 return 0;
 167
 168         idx = index_in_strings(dhcp_option_strings, opt); /* NB: was strcasecmp! */
 169         if (idx < 0)
 170                 return 0;
 171         option = &dhcp_options[idx];
 172
 173         retval = 0;
 174         do {
 175                 val = strtok(NULL, ", \t");
 176                 if (!val) break;
 177                 length = dhcp_option_lengths[option->flags & TYPE_MASK];
 178                 retval = 0;
 179                 opt = buffer; /* new meaning for variable opt */
 180                 switch (option->flags & TYPE_MASK) {
 181                 case OPTION_IP:
 182                         retval = read_ip(val, buffer);
 183                         break;
 184                 case OPTION_IP_PAIR:
 185                         retval = read_ip(val, buffer);
 186                         val = strtok(NULL, ", \t/-");
 187                         if (!val)
 188                                 retval = 0;
 189                         if (retval)
 190                                 retval = read_ip(val, buffer + 4);
 191                         break;
 192                 case OPTION_STRING:
 193 #if ENABLE_FEATURE_RFC3397
 194                 case OPTION_STR1035:
 195 #endif
 196                         length = strlen(val);
 197                         if (length > 0) {
 198                                 if (length > 254) length = 254;
 199                                 opt = val;
 200                                 retval = 1;
 201                         }
 202                         break;
 203                 case OPTION_BOOLEAN:
 204                         retval = read_yn(val, buffer);
 205                         break;
 206                 case OPTION_U8:
 207                         buffer[0] = strtoul(val, &endptr, 0);
 208                         retval = (endptr[0] == '\0');
 209                         break;
 210                 /* htonX are macros in older libc's, using temp var
 211                  * in code below for safety */
 212                 /* TODO: use bb_strtoX? */
 213                 case OPTION_U16: {
 214                         unsigned long tmp = strtoul(val, &endptr, 0);
 215                         *result_u16 = htons(tmp);
 216                         retval = (endptr[0] == '\0' /*&& tmp < 0x10000*/);
 217                         break;
 218                 }
 219                 case OPTION_S16: {
 220                         long tmp = strtol(val, &endptr, 0);
 221                         *result_u16 = htons(tmp);
 222                         retval = (endptr[0] == '\0');
 223                         break;
 224                 }
 225                 case OPTION_U32: {
 226                         unsigned long tmp = strtoul(val, &endptr, 0);
 227                         *result_u32 = htonl(tmp);
 228                         retval = (endptr[0] == '\0');
 229                         break;
 230                 }
 231                 case OPTION_S32: {
 232                         long tmp = strtol(val, &endptr, 0);
 233                         *result_u32 = htonl(tmp);
 234                         retval = (endptr[0] == '\0');
 235                         break;
 236                 }
 237                 default:
 238                         break;
 239                 }
 240                 if (retval)
 241                         attach_option(opt_list, option, opt, length);
 242         } while (retval && option->flags & OPTION_LIST);
 243         return retval;
 244 }
 245
 246 static int read_staticlease(const char *const_line, void *arg)
 247 {
 248         char *line;
 249         char *mac_string;
 250         char *ip_string;
 251         uint8_t *mac_bytes;
 252         uint32_t *ip;
 253
 254         /* Allocate memory for addresses */
 255         mac_bytes = xmalloc(sizeof(unsigned char) * 8);
 256         ip = xmalloc(sizeof(uint32_t));
 257
 258         /* Read mac */
 259         line = (char *) const_line;
 260         mac_string = strtok(line, " \t");
 261         read_mac(mac_string, mac_bytes);
 262
 263         /* Read ip */
 264         ip_string = strtok(NULL, " \t");
 265         read_ip(ip_string, ip);
 266
 267         addStaticLease(arg, mac_bytes, ip);
 268
 269         if (ENABLE_FEATURE_UDHCP_DEBUG) printStaticLeases(arg);
 270
 271         return 1;
 272 }
 273
 274
 275 struct config_keyword {
 276         const char *keyword;
 277         int (*handler)(const char *line, void *var);
 278         void *var;
 279         const char *def;
 280 };
 281
 282 static const struct config_keyword keywords[] = {
 283         /* keyword       handler   variable address               default */
 284         {"start",        read_ip,  &(server_config.start_ip),     "192.168.0.20"},
 285         {"end",          read_ip,  &(server_config.end_ip),       "192.168.0.254"},
 286         {"interface",    read_str, &(server_config.interface),    "eth0"},
 287         /* Avoid "max_leases value not sane" warning by setting default
 288          * to default_end_ip - default_start_ip + 1: */
 289         {"max_leases",   read_u32, &(server_config.max_leases),   "235"},
 290         {"remaining",    read_yn,  &(server_config.remaining),    "yes"},
 291         {"auto_time",    read_u32, &(server_config.auto_time),    "7200"},
 292         {"decline_time", read_u32, &(server_config.decline_time), "3600"},
 293         {"conflict_time",read_u32, &(server_config.conflict_time),"3600"},
 294         {"offer_time",   read_u32, &(server_config.offer_time),   "60"},
 295         {"min_lease",    read_u32, &(server_config.min_lease),    "60"},
 296         {"lease_file",   read_str, &(server_config.lease_file),   LEASES_FILE},
 297         {"pidfile",      read_str, &(server_config.pidfile),      "/var/run/udhcpd.pid"},
 298         {"siaddr",       read_ip,  &(server_config.siaddr),       "0.0.0.0"},
 299         /* keywords with no defaults must be last! */
 300         {"option",       read_opt, &(server_config.options),      ""},
 301         {"opt",          read_opt, &(server_config.options),      ""},
 302         {"notify_file",  read_str, &(server_config.notify_file),  ""},
 303         {"sname",        read_str, &(server_config.sname),        ""},
 304         {"boot_file",    read_str, &(server_config.boot_file),    ""},
 305         {"static_lease", read_staticlease, &(server_config.static_leases), ""},
 306         /* ADDME: static lease */
 307 };
 308 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
 309
 310
 311 /*
 312  * Domain names may have 254 chars, and string options can be 254
 313  * chars long. However, 80 bytes will be enough for most, and won't
 314  * hog up memory. If you have a special application, change it
 315  */
 316 #define READ_CONFIG_BUF_SIZE 80
 317
 318 void read_config(const char *file)
 319 {
 320         FILE *in;
 321         char buffer[READ_CONFIG_BUF_SIZE], *token, *line;
 322         unsigned i, lineno;
 323
 324         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
 325                 keywords[i].handler(keywords[i].def, keywords[i].var);
 326
 327         in = fopen_or_warn(file, "r");
 328         if (!in)
 329                 return;
 330
 331         lineno = 0;
 332         while (fgets(buffer, READ_CONFIG_BUF_SIZE, in)) {
 333                 lineno++;
 334                 /* *strchrnul(buffer, '\n') = '\0'; - trim() will do it */
 335                 *strchrnul(buffer, '#') = '\0';
 336
 337                 token = strtok(buffer, " \t");
 338                 if (!token) continue;
 339                 line = strtok(NULL, "");
 340                 if (!line) continue;
 341
 342                 trim(line); /* remove leading/trailing whitespace */
 343
 344                 for (i = 0; i < ARRAY_SIZE(keywords); i++) {
 345                         if (!strcasecmp(token, keywords[i].keyword)) {
 346                                 if (!keywords[i].handler(line, keywords[i].var)) {
 347                                         bb_error_msg("can't parse line %u in %s at '%s'",
 348                                                         lineno, file, line);
 349                                         /* reset back to the default value */
 350                                         keywords[i].handler(keywords[i].def, keywords[i].var);
 351                                 }
 352                                 break;
 353                         }
 354                 }
 355         }
 356         fclose(in);
 357
 358         server_config.start_ip = ntohl(server_config.start_ip);
 359         server_config.end_ip = ntohl(server_config.end_ip);
 360 }
 361
 362
 363 void write_leases(void)
 364 {
 365         int fp;
 366         unsigned i;
 367         time_t curr = time(0);
 368         unsigned long tmp_time;
 369
 370         fp = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 371         if (fp < 0) {
 372                 return;
 373         }
 374
 375         for (i = 0; i < server_config.max_leases; i++) {
 376                 if (leases[i].yiaddr != 0) {
 377
 378                         /* screw with the time in the struct, for easier writing */
 379                         tmp_time = leases[i].expires;
 380
 381                         if (server_config.remaining) {
 382                                 if (lease_expired(&(leases[i])))
 383                                         leases[i].expires = 0;
 384                                 else leases[i].expires -= curr;
 385                         } /* else stick with the time we got */
 386                         leases[i].expires = htonl(leases[i].expires);
 387                         // FIXME: error check??
 388                         full_write(fp, &leases[i], sizeof(leases[i]));
 389
 390                         /* then restore it when done */
 391                         leases[i].expires = tmp_time;
 392                 }
 393         }
 394         close(fp);
 395
 396         if (server_config.notify_file) {
 397 // TODO: vfork-based child creation
 398                 char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
 399                 system(cmd);
 400                 free(cmd);
 401         }
 402 }
 403
 404
 405 void read_leases(const char *file)
 406 {
 407         int fp;
 408         unsigned i;
 409         struct dhcpOfferedAddr lease;
 410
 411         fp = open_or_warn(file, O_RDONLY);
 412         if (fp < 0) {
 413                 return;
 414         }
 415
 416         i = 0;
 417         while (i < server_config.max_leases
 418          && full_read(fp, &lease, sizeof(lease)) == sizeof(lease)
 419         ) {
 420                 /* ADDME: is it a static lease */
 421                 uint32_t y = ntohl(lease.yiaddr);
 422                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 423                         lease.expires = ntohl(lease.expires);
 424                         if (!server_config.remaining)
 425                                 lease.expires -= time(NULL);
 426                         if (!(add_lease(lease.chaddr, lease.yiaddr, lease.expires))) {
 427                                 bb_error_msg("too many leases while loading %s", file);
 428                                 break;
 429                         }
 430                         i++;
 431                 }
 432         }
 433         DEBUG("Read %d leases", i);
 434         close(fp);
 435 }